My first suggestion would be Heucheras, no shaded border should be without them! ;-) Impatiens will do well in moist shade, there are lots of forms available. Cuphea has also done well for me in part shade, it's a very nice, bushy plant that flowers all thru the summer. Zaluzianskya capensis is a wonderfully fragrant annual, and thrives in the shade. The last two are also quick and very easy to start from seeds.

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Zaluzianskya capensis

This border was new last summer, and is shaded by a big shrub for most of the day:

Not fragrant but not commonplace: Lobelia "Monet Moment." Much better than the average Lobelia and a good strong pink.

For perennials, definitely heucheras, perennial geraniums, tricytris, hosta, saxifrage, violas & violets, hellebores...

I don't plant as many annuals (because who wants to replant every season?), but in a problem bed under a maple, I've used torenia, & it was great, bloomed all summer...

i know its 'common' but you can't beat one of the fragrant hostas-- aphrodite. great leaves all summer. then beautiful fragrant white flowers in august. some of the iris might take shade and still bloom, but hardiness could be a problem. star of bethlehem is cute in the spring (start of june), but can be invasive. foxgloves would like medium shade and sweet woodruff would be a nice ground cover for you, so would european ginger. columbines, bunneria, lobelia
pansies--violas,primroses (hardiness), there are some clematis that are short/non-vining types(hardiness), perennial bachaleor buttons.

diggerb